Giant, planetary scale, impacts can occur anywhere in a planetary system, from the innermost to the outermost regions. Giant impacts produce debris discs with distinctive features, such as dramatic, large scale asymmetries. I will discuss the origins and nature of these asymmetries and their lifetimes and show that at large orbital radii these features will be long-lived and detectable. A number of known debris discs display large asymmetries and I will show that giant impacts can provide a good explanation for the asymmetries in some of these systems.